This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Sex steroids in the brain regulate reproductive behaviors and have regulatory functions beyond the influence on reproduction. For instance, natural and synthetic androgens can induce psychiatric disorders such as anxiety and depression. Knowledge that androgens can modulate specific cellular substrates such as neuropeptides and growth factors has raised relevant questions regarding the cellular mechanisms responsible for the observed behavioral changes under physiological or abused concentrations. Neuropeptides have been associated with reproductive and anxiety-related behaviors. NPY and opioids, are highly expressed in brain regions that mediate reproductive behaviors and anxiety, but also they have been shown to be under hormonal control. However, the cellular events implied in these behaviors are poorly understood and have been addressed mainly in vivo. This proposal studies the biochemical basis underlying reproductive and anxietyrelated behaviors using an in vitro system. Isolated cells from the medial preoptic area and amygdala complex, will be exposed to testosterone and the anabolic androgenic steroid (AAS), 17[unreadable]-methyltestosterone. Cultured cells will be isolated from peripubertal rats, since puberty is a critical developmental period susceptible to hormonal and behavioral changes, and for the alarming increase in adolescents misusing AAS. Immunocytochemistry and radioimmunoassay for NPY and _-endorphin will be used to quantify IR-cells and peptide levels, respectively. Also, mRNA expression for growth factor receptors will be determined. The presence of growth factors and their receptors in the brain might suggest an important role in peptide regulation and therefore, in neuroendocrine function and anxiety. Finally, neuropeptide agonist and antagonists will be centrally infused in vivo to brain regions associated with reproductive and affective behaviors. This aim will encompass a proof of concept between the in vitro and in vivo experiments. These studies will provide critical data regarding the biochemical aspects of psychiatric symptoms associated with androgen exposure.